Hi @christopherc - Yes, I've experienced issues with long car rides when my PMR was active. I still have the same problem with long car rides even though my PMR is in remission. Here's an explanation of sorts...

"PMR aches may be worse in the morning and get better as the day goes by. Being inactive for a long time, like on a long car ride, may make stiffness worse."
-- PATIENT FACT SHEET - American College of Rheumatology: https://www.rheumatology.org/Portals/0/Files/Polymyalgia-Rheumatica-Fact-Sheet.pdf

Hoping your PMR goes into remission soon!